It is known that alpha olefins may be oligomerized to prepare synthetic oil base stocks, but many of these oligomerization products do not have the physical properties desired for certain applications, and they are often expensive to manufacture.
U.S. Pat. No. 5,304,615 discloses a process for the polymerization of butene using an ionic liquid as a catalyst, but the disclosure does not suggest a continuous process or the use of an ionic liquid composition derived from the combination of an alky-containing amine hydrohalide salt and a metal halide.
U.S. Pat. No. 5,731,101 discusses the possible use of low temperature ionic liquids as a catalyst for dimerization, oligomerization, and polymerization, but it does not specifically teach the oligomerization or polymerization of alpha olefins; and, moreover, there is no suggestion of a continuous process using an ionic liquid to make polyalphaolefin products that are useful as lubricants or lubricant additives.
U.S. Pat. No. 5,824,832 is a continuation-in-part of U.S. Pat. No. 5,731,101 discussed above, and it focuses on the use of ionic liquids in the alkylation of aromatic molecules. The only exemplified reactions are those involving an aromatic compound, such as benzene and toluene. There is no suggestion of a continuous process using an ionic liquid to make a polyalphaolefin product.
EP 0791643 discloses a process for making lubricating oils by oligomerization of alpha olefins in the presence of an ionic liquid, but it does not teach the use of an ionic liquid composition derived from the combination of an alkyl-containing amine hydrohalide salt and a metal halide nor does it teach a continuous process.
Considering the above discussed prior art, it is clear that there is a need for an economical process that utilizes the advantages of continuous processing for the manufacture of a polyalphaolefin product having certain desirable physical properties.